Antenna and non-contact tag

• US 20070200711A1
• Filed: 04/26/2007
• Published: 08/30/2007
• Est. Priority Date: 12/14/2004
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kai, Manabu, Maniwa, Toru, Yamagajo, Takashi
• Granted Patent: US 7,570,225 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

An RFID antenna that can be disposed in a space-saving manner. The RFID antenna comprises an outermost peripheral conductive line that is bent in a manner extending along sides of a generally rectangular shape having a predetermined size, and a power-feeding conductive line that is disposed close to an inner periphery of the outermost peripheral conductive line in a manner extending parallel therewith, and is electrically connected to the outermost peripheral conductive line at ends thereof, the power-feeding conductive line including a portion thereof formed with a feeder part. Therefore, the antenna fits into a rectangle having a predetermined size, such as a card size.

Claims

1. An antenna for RFID, comprising:

an outermost peripheral conductive line that is bent in a manner extending along sides of a generally rectangular shape having a predetermined size; and

a power-feeding conductive line that is disposed close to an inner periphery of said outermost peripheral conductive line in a manner extending parallel therewith, and is electrically connected to said outermost peripheral conductive line at ends thereof, said power-feeding conductive line including a portion formed with a feeder part.

2. The antenna according to claim 1, wherein said outermost peripheral conductive line is formed to have a sufficient length for receiving radio waves in a UHF band.

3. The antenna according to claim 1, wherein a ratio between a line width of said power-feeding conductive line and a line width of said outermost peripheral conductive line is adjusted, whereby radiation resistance is adjusted as desired.

4. The antenna according to claim 1, wherein an impedance-adjusting inductor for performing impedance matching with an IC chip connected to said feeder part is disposed in an area inside the generally rectangular shape.

5. The antenna according to claim 4, wherein a bent portion of said inductor is bent in a curved manner.

6. The antenna according to claim 4, wherein said inductor is linearly connected to two opposite sides of a generally rectangular shape into which said power-feeding conductive line is bent.

7. The antenna according to claim 1, wherein said outermost peripheral conductive line and said power-feeding conductive line are formed asymmetrically with respect to said feeder part.

8. The antenna according to claim 1, wherein a portion of said outermost peripheral conductive line is formed by being bent into an inside of the generally rectangular shape, said portion having a length by which an outer periphery of the generally rectangular shape thereof is short of a length required for receiving electromagnetic waves of a predetermined frequency.

9. The antenna according to claim 1, wherein said outermost peripheral conductive line or said power-feeding conductive line has bent portions thereof bent at an angle of 90 degrees.

10. The antenna according to claim 1, wherein said outermost peripheral conductive line or said power-feeding conductive line has bent portions thereof bent in a curved manner.

11. An antenna for RFID, comprising:

an outermost peripheral conductive line that is bent in a manner extending along sides of a generally rectangular shape having a predetermined size;

a power-feeding conductive line that is disposed close to an inner periphery of said outermost peripheral conductive line in a manner extending parallel therewith, and is electrically connected to said outermost peripheral conductive line at ends thereof, said power-feeding conductive line including a portion formed with a feeder part; and

an impedance-adjusting inductor for performing impedance matching with an IC chip connected to said feeder part.

12. The antenna according to claim 11, wherein said impedance-adjusting inductor is disposed in an area inside the generally rectangular shape.

13. A non-contact tag for RFID, comprising:

an antenna including an outermost peripheral conductive line that is bent in a manner extending along sides of a generally rectangular shape having a predetermined size, and a power-feeding conductive line that is disposed close to an inner periphery of said outermost peripheral conductive line in a manner extending parallel therewith, and is electrically connected to said outermost peripheral conductive line at ends thereof, said power-feeding conductive line including a portion formed with a feeder part; and

an IC chip connected to said feeder part.